Metal modified biochar capable of efficiently recycling and desorbing phosphorus as well as preparation method and application of metal modified biochar

The invention discloses metal modified biochar capable of efficiently recycling and desorbing phosphorus as well as a preparation method and application of the metal modified biochar. The preparation method of the metal modified biochar comprises the following steps: (1) crushing, sieving, cleaning and drying biomass walnut shells to obtain walnut shell particles; (2) soaking the walnut shell particles in a metal salt solution, stirring for 24 hours or more at normal temperature, and then drying to obtain a metal-modified walnut shell raw material; and (3) heating the metal-modified walnut shell raw material to 300-700 DEG C in a protective gas atmosphere, preserving heat for 2 hours or more, and carbonizing to obtain the metal-modified biochar capable of efficiently recycling and desorbing phosphorus. The metal modified biochar has double purposes: phosphorus in a phosphorus-rich water body can be efficiently adsorbed, and the biochar particles recycled after adsorption can be desorbed to release phosphorus